Acid nickel electroplating baths and processes



United States Patent Ofifice 3,314 868 ACID NICKEL ELECT ROPLATING BATHS AND PROCESSES Wolf-Dieter Willmund and Wennemar Strauss, Dusseldorf-Holthausen, Germany, assignors to Dehydag Deutsche Hydrierwerke G.m.b.H., Dusseldorf, Germany, a corporation of Germany Drawing. Filed Jan. 28, 1964, Ser. No. 340,787 Claims priority, application Germany, May 15, 1963, D 41,559 20 Claims. (Cl. 204-49) This invention relates to a process for nickel electroplating and to a nickel electroplating bath containing additive compounds. It more specifically relates to the use of aromatic nitrogen compounds as leveling additives for nickel electroplating baths.

It is already known to use reaction products of hetero cyclic nitrogen bases of the aromatic type with sultones as leveling agents in nickel electroplating baths. Accord ing to their chemical structure, these products are inner salts of amino-alkane-sulfonic acids, so-called sulfobetaines. The leveling effect of these products is entirely effect may be adversely affected.

It is, therefore, an object of this invention to provide a during operation of the electroplating process.

Another object is nickel electroplating which produces an improved leveling effect and leveling depth distribution.

These and other objects of our invention will become apparent as the description thereof proceeds.

It has now been found that the objects of the invention may be attained and the disadvantages of the prior art overcome by use of organic betaine additives of the general formula wherein represents a member selected from the group consisting of monoand polynuclear aromatic heterocyclic nitrogen base groups having at least one nitrogen atom.

R, R and R represent the substituents CH C H or another alkyl substituent, which may also be omitted. R is an alkylene radical with l to 12 carbon atoms phosphoric acid ester radical wherein at least one -R X radical is present in the molecule attached to a nitrogen atom.

The betaine compounds according to the present in- The betaine compounds may also be derived from heterocyclic nitrogen bases which comprise two or more ring system, which may be, for exmple, pyridazine, pyrimidine, pyrazine, phthalazine, quinazoline, quinoxaline, phenazine, and the like, where 3,314,868 Patented Apr. 18, 1967 the acid alkanic acid ester radical (-R -X*) may also be present on several ring nitrogen atoms.

The additives may be used in nickel electroplating baths, for example, a Watts type nickel plating bath. The baths products according to the present inven- In addition to the leveling agents according to the present invention, the nickel electroplating baths may be modified with customary brightening agents well known in the art, such as benzene-m-disulfonic acid, diaryldisulfimides, sulfonamides and the like, and also with other known agents, such as wetting agents.

Example I The leveling agent according to the may be prepared by pyridine were added present invention the following method. 85.7 gm. of dropwise at to -C. over the over the course Subsequently, the mixture was heated to 40 C. in the course of 60 minutes, then stirred for one hour. Nitrogen was then passed therethrough for two hours to drive oil the hydrogen chloride formed by heating, and then the mixture was stirred for two additional vhours at 35 to 40 C. The solid substance Example II A nickel bath of the Watts-type was modified with 2 gm./l. of o-toluene-disulfonimide as a brightening agent,

In the nickel bath described in Example I the leveling agent was replaced by an equal amount of pyridinium- (decy-lsulfate-) betaine. An equally good leveling effect of the nickel electrodeposits was achieved even down to a current density range of 0.1 amp/dm.

Example IV In a nickel bath of the Watts-type, 3 gm./l. of N (benzene'sulfonyl)=benzoylarnide were dissolved as a brightening agent, 0.5 gm./l. of sodium dodecylsulfate as a wetting agent and 0.2 gm./l. of .py-ridinium(ethylphosphate-Z) betaine as a leveling agent. This bath furnished full bright, ductile and well-leveled nickel electrodeposits at an operating temperature of 50 to 60 C. in a current density range of 0.25 to 7 amp/drnfl.

Example V In the nickel bath of Example IV the pyridinium-(ethylphosphate-2) betaine was replaced by the same amount of w-picolinium-ethylsulfate-Z) betaine as a leveling agent. Nickel electrodeposits of equally good quality were obtained.

Example VI A nickel bath of the Watts-type was modified with 1.5 gm./l. of N-(benzene-sulfonyl)acct-amide as a brightening agent, 0.5 gm./l. of sodium dodecylsulfate as a wetting agent and 0.3 gm./l. of pyridinium-(3,-dioxaoctylsulfate-8) betaine as a leveling agent. Full bright, ductile and high-level nickel electrodeposits were obtained at a bath temperature of 50 to 60 C. in a current density range of 0.5 to 8 amp/dnm While certain specific examples and preferred modes of practice of the invention has been set forth it will be understood that this is solely for the purpose of illustration and that various changes and modifications may be made without departing from :the spirit of the disclosure and the scope of the appended claims.

We claim:

1. An aqueous acid nickel electroplating bath for obtaining level nickel electrodeposits, which comprises an organic betaine additive compound of the general formula wherein represents a member selected from the group consisting of monoand polynuclear aromatic heterocyclic nitrogen base groups having at least one nitrogen atom,

wherein a radical -R -X- is attached to at least one nitrogen atom of said aromatic heterocyclic base group, said additive being added in sufficient amount to obtain said level nickel deposits.

4 2. An aqueous acid nickel electroplating bath, which comprises an organic betaine additive compound of the general formula wherein represents a member selected from the group consisting of monoand polynuclear aromatic heterocyclic nitrogen base groups having at least one nitrogen atom,

R, R and R are selected from the group consisting of hydrogen and alkyl groups,

R is an aliphatic radical with 1 to 12 carbon atoms,

and

X is selected from the group consisting of an acid sulfuric acid ester radical and an acid phosphoric acid ester radical,

wherein a radical -R X is attached to at least one nitrogen atom of said aromatic heterocyclic base group, said additive being added in an amount from about 0.05 to 3 gm./l.

3. An aqueous acid nickel electroplating bath, which comprises an organic betaine additive compound of the general formula wherein represents a member selected from the group consisting of monoand polynuclear aromatic heterocyclic nitrogen base groups having at least one nitrogen atom,

R, R and R are selected from the group consisting of hydrogen and alkyl groups,

R is an aliphatic radical with 1 to 12 carbon atoms,

and

X is selected from the group consisting of an acid sulfuric acid ester radical and an acid phosphoric acid ester radical,

wherein a radical R X" is attached to at least one nitrogen atom of said aromatic heterocyclic base group, said additive being added in an amount from about 0.01 to 0.05 gm./l.

4. The bath of claim 1 wherein said additive is a pyridiniumalkane sulfate betaine.

5. The bath of claim 1 wherein said additive is a pyridiniumalkane phosphate betaine.

6. An aqueous acid nickel electroplating bath comprising as an additive compound from about 0.05 to 3 gm./l. of pyridinium-(ethylsulfate-2) betaine.

7. An aqueous acid nickel electroplating bath comprising as an additive compound from about 0.05 to 3 gm./l.v of pyridinium-(decylsulfate-lO) betaine.

8. An aqueous acid nickel electroplating bath comprisas an additive compound from about 0.05 to 3 gm./1. of

wherein represents a member selected from the group consisting of monoand polynuclear aromatic heterocyclic nitrogen base groups having at least one nitrogen atom,

R, R and R are selected from the group consisting of hydrogen and alkyl groups,

R is an aliphatic radical with 1 to 12 carbon atoms,

X is selected from the group consisting of an acid sulfuric acid ester radical and an acid phosphoric acid ester radical,

wherein a radical -R -X is attached to at least one nitrogen atom of said aromatic heterocyclic base group, said compound being added in sufiicient amount to obtain said level nickel electrodeposits.

12. A method for producing level nickel electrodeposits which comprises forming said electrodeposits in an aqueous acid nickel electroplating bath to which has been added a betaine compound of the general formula wherein represents a member selected from the group consisting of monoand polynuclear heterocyclic nitrogen base groups having at least one nitrogen atom,

wherein a radical -R -X is attached to at least one nitrogen atom of said aromatic heterocyclic base group, said additive being added in an amount from 0.05 to 3 gm./l.

13. A method for producing level nickel electrodeposits which comprises forming said electrodeposits in an aque- 6 ous acid nickel electroplating bath to which has been added a betaine compound of the general formula 2 wherein represents a member selected from the group consisting of monoand polynuclear aromatic heterocyclic nitrogen base groups having at least one nitrogen atom,

R, R and R are selected from the group consisting of hydrogen and alkyl groups,

R is an aliphatic radical with 1 to 12 carbon atoms,

and

X is selected from the group consisting of an acid sulfuric acid ester radical and an acid phosphoric acid ester radical,

wherein a radical -R -X-' is attached to at least one nitrogen atom of said aromatic heterocyclic base group, said additive being added in an amount from about 0.01 to 0.05 gm./l.

14. The process of claim 11 wherein said additive is a pyridinium-alkane sulfate betaine.

15. The process of claim 11 wherein said additive is a pyridinium-alkane phosphate betaine.

16. The process of claim 11 comprising as said additive compound from about 0.05 to 3 gm./l. of pyridinium- (ethylsulfate-Z) betaine.

17. The process of claim 11 comprising as said additive compound from about 0.05 to 3 gm./l. of pyridinium- (decylsulfate-IO) betaine.

18. The process of claim 11 comprising as said additive compound from about 0.05 to 3 gm./l. of pyridnium- (ethylphosphate-Z) betaine.

19. The process of claim 11 comprising as said additive compound from about 0.05 to 3 gm./l. of 'y-picolinium-(ethylsulfate-2) betaine.

20. The process of claim 11 comprising as said additive compound from about 0.05 to 3 gm./l.. of pyridinium-(3,6-dioxaoctylsulfate-8) betaine.

References Cited by the Examiner UNITED STATES PATENTS JOHN H. MACK, Primary Examiner. MURRAY TILLMAN, Examiner. G. KAPLAN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,314,868 April 18, 1967 WolfDieter Willmund et al.

at error appears in the above numbered pat- It is hereby certified bh tters Patent should read as ent requiring correction and that the said Le correctedbelow.

Column 4, line 67, for "compris-" read comprising llne 71, for "pyridinium" read y picolinium Signed and sealed this 14th day of November 1967.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

1. AN AQUEOUS ACID NICKLE ELECTROPLATING BATH FOR OBTAINING LEVEL NICKEL ELECTRODEPOSITS, WHICH COMPRISES AN ORGANIC BETAINE ADDITIVE COMPOUND OF THE GENERAL FORMULA 